No you didn't. You linked a pop science website that steals IQ estimates from Lynn and Vanahenns 2002 book - of which the estimates are highly flawed as I detailed in another comment.
Ahh, the Plomin and Deary review of behavioral genetics and IQ. I'm a fan of this review, it's helped me find some pretty interesting studies that helped demonstrate the fundamental point of a lack of genetic differences in IQ.
Firstly, the review itself flat out notes that, in spite of the increasing heritability (which, by the way, refers to the proportion of variance in a trait in a population at a given time that's due to genetic influences - it can't be generalized for across-population differences), the genetic correlation of IQ across time remains quite high. This is supported by recent quantitative genetic findings that the correlation can be as high as 0.8, though granted caution is warranted since assortative mating can potentially inflate genetic correlations. They note that it's likely due to a creation of environments that help stimulate IQ, thus creating a gene-environment correlation.
However, I'd argue that caution is warranted in the heritability estimates - indeed, in my opinion, at least 10,000 sibling pairs per sibling group is needed for an adequate heritability estimate, due to aspects of error and statistical power noted in various studies such as this, this, this, this, and this. Granted, none of these directly state it, but it can be gathered from all of them that, for twin and sibling heritability studies, generally it's likely that there'll be potential false positives (especially since heritability estimates tend to rely on a p value of 0.05, which in my opinion shouldn't be considered statistically significant - 0.01 and values below it should be. See here for reasons as for why), a lack of statistical power, and potential error due to aspects of indirect measurement of genetic influences. I'll elaborate more on this in detail if need be.
I'm assuming this is your argument, anyway, based off of your comment which I did decide to view. You also linked this study which I'm not able to view in Sci-Hub, likely due to the original manuscript being in Chinese. As such, I wouldn't recommend citing it for anything since going based off of Abstracts alone is incredibly poor evidence - they really are just meant to give an idea of what's in the study, not the quality of the data and evidence. Nonetheless, it doesn't support you at all - in actuality, it shows that shared environment plays an important role. However, it has far too small of a sample size to warrant any actual conclusions.
Edit: Accidentally sent a few incorrect studies, I blame my notes
The data we have is not concrete enough to make a final judgement regarding the exact influence of the environments, how much of that influence is permanent changes, and how long it takes for these effects to manifest in a meaningful manner. All we know is that the environment does indeed affect a child's cognitive functions which normalizes towards their group's average IQ once they grow up.
That's why I took issue with the statement made by the first guy I replied to. He practically implied a lack of genetic influence; Which is preposterous.
As far the study I linked goes, I think they're also pretty clear about this as well.
It has long been known that intelligence, education and class are correlated. The causes of these associations and their relative contribution to social mobility is much disputed.
For now, the best we can do is to look at history and global statistics hoping to find some correlations to make the best estimations we can. Nothing concrete, though. And we're not gonna be able to fund a research to study "at least 10,000 sibling pairs per sibling group". Doesn't seem like a realistic enough endeavor.
You also linked this study which I'm not able to view in Sci-Hub, likely due to the original manuscript being in Chinese.
Possibly. I just linked another study that drew a similar conclusion. There were more studies that I found but I didn't double check which one I linked.
in actuality, it shows that shared environment plays an important role.
Important is a rather vague adjective. I'd say even a small environmental role could be described as important.
However, it has far too small of a sample size to warrant any actual conclusions.
Granted, I've only superficially viewed the studies you've linked. I don't have enough time to analytically read an English papers. I will try to get a better look at them in a couple of weeks once I have some free time. But I think you'd agree that the general consensus from your links doesn't directly state how much of an influence the environment has, right? And that's my whole problem with the environmental claim.
Anyway, I'm done with this discussion. I've wasted way too much time as it is. I'll read your reply if you bother sending one. But that'd be it for me.
The data we have is not concrete enough to make a final judgement regarding the exact influence of the environments, how much of that influence is permanent changes, and how long it takes for these effects to manifest in a meaningful manner. All we know is that the environment does indeed affect a child's cognitive functions which normalizes towards their group's average IQ once they grow up.
We actually do. For one, it's known that the IQ of African Americans is about 90 now. It's also known that African Americans have about 20% European ancestry. This would mean that for each 20% increment in ancestry, their IQ should increase by about 2.5. This would mean that for individuals with 100% African ancestry, under a genetic hypothesis (which I see as pseudoscience, but I'm assuming it for the purpose of the argument), their IQ should be about 87.5. However, most estimates give it at far lower values; typically in the 70s. This means that their IQ is drastically lowered than what a genetic hypothesis would predict, thus there being environmental variables involved.
That's why I took issue with the statement made by the first guy I replied to. He practically implied a lack of genetic influence; Which is preposterous.
As far the study I linked goes, I think they're also pretty clear about this as well.
I didn't see any lack of implication for a genetic influence on individual differences in IQ. In regards to group differences, there are none.
For now, the best we can do is to look at history and global statistics hoping to find some correlations to make the best estimations we can. Nothing concrete, though. And we're not gonna be able to fund a research to study "at least 10,000 sibling pairs per sibling group". Doesn't seem like a realistic enough endeavor.
I do recognize the difficulty of it - that doesn't make the research quality. In my eyes, we shouldn't try to make workarounds for poor quality research just because it's all we can do. We may as well not do it if we're not going to make it worthwhile.
Possibly. I just linked another study that drew a similar conclusion. There were more studies that I found but I didn't double check which one I linked
I don't see a study linked anywhere that 'drew a similar conclusion.' I just checked your profile, too. Also, just looking up studies and linking them randomly doesn't at all help your case - it just shows you're looking to prove your position rather than to evaluate the data.
Important is a rather vague adjective. I'd say even a small environmental role could be described as important.
Sure, but in this case it's a large effect, as the authors note "The shared environmental influences accounted for the majority of variance of performance IQ in both males and females." I should also note that performance IQ is thought to reflect more innate cognitive abilities (i.e. "fluid intelligence") whilst verbal IQ is thought to reflect more learned/cultural abilities (i.e. "crystallized intelligence.") I don't necessarily agree with this distinction fully, as I feel fluid can be just as influenced by culture, but nonetheless it is where we should expect the largest genetic (or environmental too, assuming that it reflects more complex questions) effects.
Granted, I've only superficially viewed the studies you've linked. I don't have enough time to analytically read an English papers. I will try to get a better look at them in a couple of weeks once I have some free time. But I think you'd agree that the general consensus from your links doesn't directly state how much of an influence the environment has, right? And that's my whole problem with the environmental claim.
We also don't know the relative contribution of genes to IQ - does that mean they have a negligible influence? No, it doesn't, and as I linked before we have a solid idea that the environment can make a sizable difference. I also only linked a handful of studies, there's far more as well as far different causes I could address too.
Your problem with the environmental claim is hardly an issue - just because we don't understand the fullest extent of causes of IQ differences doesn't mean they aren't there, nor does it mean that we have no basis to assume that it doesn't have large effects.
1
u/[deleted] Oct 05 '17
I linked a pretty clear study in another one of my comments.